SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ea62dcccc2986b714b131344a916240b36e03ae1bb7a192f745c542713bdaf08' 
  AND token = '2l8fqW+d05VrsTvhTyxWUore8W45zdcfSdbkYKLwweo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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