SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0a943d1eb3a56ce8938242c2613e7d35c3f1ee17fbaf8acac89cc077b86bf309' 
  AND token = '64Znt4RClVbQBBqWrWYnw1l0cQxvmvhoXxgRVUvwXp8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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