SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6b3b5ae73a8c2fd6ee86fb9d747d3a55d630799b4ff567102465c53b9505d0c1' 
  AND token = 'I8PDaCxmpcc/sMRf+hpJ/wdpB/XmqjcsHyhz2bvOZnI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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