SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd249e41558fe0835a7ab9203c5500846a7625788c9239925b31830c438450e9e' 
  AND token = 'eWA+vrbR3zzKKJJl4JcEgt4XSRMTqxRakw7G24epvTE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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