SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '30902da403ee5ecdddbc3fa750347cd05b281e95ad85d4ebb0ea801ddc414bdb' 
  AND token = 'q3OKUuf9jffjnk4fSDnQaU0GERrAYyYdJy6z6NCSsn4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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