SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3ae172a30f016e76eb24b421b1bbcc798b6bf6f9c08d4a141dab7a9533799378' 
  AND token = 'TBP/hL4w7CkDwFK3M6AltCuJXrmsyY1v+wLDOkLhfXc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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