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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '121cd87a84e9c19c35870941b5b710bb40a535237420cde246f4ff935b8a2ef3' 
  AND token = '4EsWlEV9RSjQ2FLZFpEqXJ+kSk4wYbcA0WAWaZFKaj0=' 
  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"
    }
  }
}