SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '81ebffa46eaf722e90e662229c196a9575579321a876b2adfb07dc9c2398ed02' 
  AND token = '53wmLRPrJQa7i+QddxPi69ALqdSImfDSU5dMJL/W7yM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}