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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c3ba889440de64711f98f6e3fe9357ea4e82a797fc281e3880b0483385c0d2f9' 
  AND token = 'dCtTGJDHmIG1OfGI7Qm6b3MUB1gmgObFMQNLc+bGmw0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}