SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ad6536a7ce6ab98f20f1546e846f824fbb3a4a785820119223ad3083509876bc' 
  AND token = 'pROrOvhHe1C6N1gIqBKuB8/xsHIq9sBBpqzT8jTcMdU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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