SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '902c3b97fe74749b6d7ccac283d4d3552bf458d883a7c57b610c8f072acc6306' 
  AND token = 'DkbcCpZZ5YZhP8BJqLYYHkbqSicTb2iOn0Gpno1cH2o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00052

JSON explain

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