SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2b76850e1e3b3e40dbb9b738271cc9c25c581017ca37331f4a6eced5dac6386f' 
  AND token = 'aXn8uQSUlrSttBI6ugmOY4tw7vCQ0BpJE4yuBH7qeOw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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