SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6d300a2721545929e84a712fc1efc5a1f140f5430e2ee92938951109fe9f5142' 
  AND token = 'rlJ1Pwop421a+Ko+xNHv3YmrwOxWrdC29qglveD+LMo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00014

JSON explain

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