SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '57ce91aee25d8d999ab29f93c637836ad7271adf648684d5d457bb5457766b4c' 
  AND token = 'zhK1D0KVNZsJpQAmntHn2r53A381+pXMdkOllxBzwV0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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