SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6238ab7a118bf88fb3accdd84be4b9fc22d6c528bcb9363182d5a06e6dda325d' 
  AND token = 'UADHRKIQrRg2aM3wb3Ek/AYe+ndx0xwbrxSgziMegq4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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