SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd475bd3a05113abc4ba1cb82a3173d0e84f2fa58d48ce698d17b635e9adbed10' 
  AND token = '/iLHY6yd3UfnIJ0BDSWB4mIyAoNG1s4EjLHjCVrPfUI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}