SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '504e591a75a8551bd1c37c7d146c3b52bf47023f1acf4e6654068218a29139ec' 
  AND token = 'u/uVOYMGAYnqhfP4OrNsZmQKvZutfLMCAnNpYSRz9bQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

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