SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cfe6df88ea281e1d11f75fb258e860281d4effb92f742863f066181c240aa65b' 
  AND token = 'BC8Ddqus4zY0GQwwskOkl+mf3lVQkdM28Caea+Vde4U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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