SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4fc9e5ee218343045283ab7c11689f1b584604970d7e40b01731924ea8a85f1e' 
  AND token = 'bb2kLb/MYfXogd7A74mYGAAWQ418wuGJtLCqmt9xD2I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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