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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b8d71a1ab8e541b2522b5afcc8762589f7b6e5360387e69243a36508612b2ba6' 
  AND token = 'W9ERtWvxLP0t9+mLQAb2q9Bjo6m8NLxUEuFpw7YahrQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}