SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4da7b36978b2b92adfd62ab736199b4f885fc5f934e84d03b6899ca53a6f44f9' 
  AND token = 'LHkiYOSqIrHxp4RpVgC7g8WY3HSDB85EJIKYcSyXCk0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00059

JSON explain

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