SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd757b2c8a3d31d161ff30d4b95181fe109dd4542f069e792563e099cb986f848' 
  AND token = 'KGfNG9SERBsEORi3HlaEu3sEFlD4uLpoaDISjMmhHfE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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