SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b2f4f193c3a699ca5d43b3992e3ef1624ee20f3257baf35d6f28c550a1c17dfb' 
  AND token = 'hI2Rq8/RRfqtZY8gy9WZBQudJiPGnvmjX4ZSpYW/+f8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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