SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '75b4c7eaf92f935385da4ffdd18c3416a779dedc80a55d85e8f306a09423d069' 
  AND token = 'vRpAgFoOkIhy8J/mwunyoGILCczxKFJozJg/L0GLA1o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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