SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '784674d0d5913ba816432504bbbf972a364a7f9bf1e06d49c74ec5367f699121' 
  AND token = 'pkyKXYxT0hOxjMFGQXZIGUjgEYq0dyO5gbY4Z+iJRGI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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