SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dacf2abbffb64559479f357fb83f1b12912a7e3dc3cbb7168afed6402a6bfb73' 
  AND token = 'BXmhQqWm0YEC6SX4DDJHv03tCvXe8Iz+qSDZoAK8aY4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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