SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '332d1eefaab95146c6ef753920386efaa2e2baf288049cb7650447434c851899' 
  AND token = '/91X6fstFAhIl7Vl9VY/M4UXfeWeK0n1NCZRP9aWfm4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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