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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a42c6a878129b3a4cc446ea0961b92ff47a08409b9dd4d89e38dc733f995d544' 
  AND token = 'Jk0ldqMJMhqD0/2egw5XECrYTMj+kV2c0Kle6fnGQcw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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