SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '47aeb2ed9be914fef6f3da0f562bf37ce2ff952a4aa40b9da91471b5d8955290' 
  AND token = 'blGFnnay9EoFVz/Ox5PW2vXWvbdxAJE5WIS97Wi46YQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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