SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7458ed00c2f09571eb1e0fae5207b8ac925f6f9300f2885200727f1549bfc630' 
  AND token = 'cjQstutM6Wf9QfftgG/MSsPn0UH8HgPJx4P8fgTnZx4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00053

JSON explain

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