SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'affe41cff798d5ec124ce688c8f929c6181909858afe4ee766569da7b96d157a' 
  AND token = 'TBgNpEEttsaFxZdW8UrhI/DjyZOwwkWyLJC+kbWpKtw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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