SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '257ce5427f9cf0d327d900f476b39e9a0dec6abdef8c34bae97327164652f613' 
  AND token = 'ILeUkc024S7BuRpVBOZPlRBMdpH7zIeEugDnWBTj0Vs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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