SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '345b69d6c369645dd202122cb181f01a079edc875c155b91d0308e70a99793bd' 
  AND token = 'Sl9m2n86NiHrVWa6IreSBCxeqUEtQwMJ1tiZdajYCss=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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