SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1e457876f296a7c5693b1cd21b54adecc3846b9e7fa84da44a0ad62511b65f82' 
  AND token = 'wFuKslcpR0hWh8icmQHQ2jEpD+Npfj9+TPFzadNSGgk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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