SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dad627794a153ea313f451f1b642c4d795a9e89333d870f989fc916962169241' 
  AND token = 'kqnddy/nFJ/TpiBKjazusbO142LmrlqRh2cwGsp+qZ4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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