SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f771b4b146dc3bc8433e20cdd89851233554e4fa1d129bb9ba7e3498f4c42b2c' 
  AND token = 'io+nqa6V9EbR+gnpIEdZ96yqv8DVm/whUFU1AYrXjwM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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