SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '12ea82b18ba2b688477765d8769aab8a3066518df14899c021475614e997c6cb' 
  AND token = 'SYZaudGpQaBdgVqZOw+xIDrJa3DAtV4/1JqNJHfJ92o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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