SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6ee6608ffd8f1778428a47eb0eeb125c7e477098f07f1f8208c6115a5d24c748' 
  AND token = 'r6omoFC6xObIXObzGos6WldUJfXNSpgvYJzqsGQYlx4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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