SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3eb0b3b91e2b442cd78300d19a18f792372e000237e73c797d1e29b2c5496d16' 
  AND token = 'AaNZOTqBrpCWFMSstCH1/YFrD5jTBQK1p4tTLZklSv4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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