SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dde870a4b76c535f2d4345e2b255838af6e85131b9f512a60b5db60c4b29f315' 
  AND token = 'WfCWiZ+kcZTxDZoJpozYCHBXtPBr+z80vN58twmgEYA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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