SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '881272604fa946dc4d0c339047bd9036035e500eee6b8cbff6c8dc8382501739' 
  AND token = '8kq6gXovuF8OWW0XCVdZITsuFtr/ea9uhPGF5gzn3Yc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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