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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '298781c6a9bc85da6b91ae1f51e1aaa99b969098f24e37b04f9ee9798178247a' 
  AND token = 'SBJWSGwuVdfRI1BYm1nQwYjAFYF/pwlxy4xNfXul5nQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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