SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a599fca3ad6531ee715859827881a9f527b967b225ea81c72941257775b3de44' 
  AND token = '1kavHB9zU0zwjI//tnmeIfGUqEet2kqQb4scqC65AiI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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