SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4ba18ba4988abad42ceb05cf2826016e7ddae552884b3792d7692db28093c166' 
  AND token = 'l18jmrJxxCDE8xg5+TBlMQ4ghwXEKhTtv+/0xRnWNRI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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