SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '27e6d0e460993b6d5d61c981529d4072bd8078ce941b0777808e3d9d59f42b00' 
  AND token = 'RcU2GxYD2ae9/yDUFdDbOey7aUzETe9g8e7PzNrncjw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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