SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4703250d0a71b9929eaa5cb2e929eed3bfa2e8ddfbbd6f393c2ce37ea8a9faba' 
  AND token = 'XsAFwOVMVRsiCkX+RDa0C+CcP+DAlPlSgJ3eq1X3ti8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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