SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '142dceaffb7a4bc507cef82543651394bd2ebb6294372684958c650720917da8' 
  AND token = 'oeTOR23gsPdys1GkmQH4kggdSZl+VNS/xvpfD61zSqk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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