SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cd9f17f6f0308577b9776eca6b7ef86946721a07920f6023647bad22a3e44a15' 
  AND token = 'k61zLufvTDTmpSqJgwxw4SRJOM/oTZlLTBDlTmoSdQw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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