SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '607e9ebae40b6549dd326abe4895c16fb579170de9de0fb9ecab06051e97ad45' 
  AND token = 'JqLsEgMAV+vre5Tb4dl8i0mA+knZ3y8M6niiMcbRK9o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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