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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c81aa8dfaec54ffe242515d4f785a4ca61c2946cb7cdc6c17e9f782f7df0cd56' 
  AND token = 'lDzI00g3CDUUynlU7mWPQNplnui0Q/jeVb06utybATY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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