SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '786c441f07a48826a9a53dc6e791f225c09f4dc1b0eb4d8f9d741b77be0c5a70' 
  AND token = 'BT2nAtKHmsHhFqoHL9SXGJbMkSbgCzak1ZcZ481yIg0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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