SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8b042ad08642b574854c494d5e2527a169762df4b900bc94c89160b197f6d0fa' 
  AND token = 'ji5BwsenZf8b0lxVcizOYWnq45GPrZUL3SWuRUJXmDo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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