SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cf01bdf7fe12a1a9cbfc596244a0d83335349389bfbed0d3d59256d884d83821' 
  AND token = '0yYhVdD4uNMjhaKzcYdt/rIWm+ck81PL5vR7MqXCLsU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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