SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6973ac0341cc8c4900b04a2fd8ce2916f8c56d1e00741344f3bc03d6932923dd' 
  AND token = 'XrfVwi/ZiWbWRS+uGt1p9TYBht4Uod8hZtvx2Sq7kP4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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