SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b1274001759b1bd3df14578a24018ad9fe9e47ad71b3b426904ccd3dc15c86fb' 
  AND token = 'q3ixOQQxWiivBF6FAf/9Xr2SJP5UWwee/fqwCHMRxUc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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