SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f675d261d013770bdd5aeb786927a59a31f1712713c530ee482f54bfecd39d1c' 
  AND token = 'sj1zZ/YriYkKJiZF0jJVwjOPUO7fj45jUbg+vavkKZg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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