SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c53099f9371c2fe10724504016a21a0bfb81fc584ef6a7b787b1b73784392181' 
  AND token = 'ncPZg34/JtzSxrpDryADBjwPPVgZLDs1k53zB+wHHJI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00015

JSON explain

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