SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '400c947a0f453661ce7de9f27b5ea31044ea81b4479a978c82770f8b87a55c52' 
  AND token = 'yvUL8G+ofqpu9doKp3cTLkRMAwHJtGSzMTlzvQV6oII=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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