SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b0e793d609095c9bb122d72e5c984a857ccb13b9acd410b54b8a52dc4cf0781f' 
  AND token = 'wOu51vO5EFk5DeCY71IKpwwjWX7z4W7vljzmTnAE0DY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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