SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '03fcc3f7440da699b579630ee7155a425758dafc3bff2cc727407f376f0df9f5' 
  AND token = 'gE2cRSJzEwzpvlR48Hd/ACV84XKfWh/UWdMGrlrny/c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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