SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '59a0656f50677373ae838104945f93f79fa220d56ed217b3081dc45620f1788f' 
  AND token = '/5PHpfBlJGx+TlN+5h2CTLCp6fsOdCyvu+KfdxuEFt8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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