SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7b4da959d4ad29da185f3d0123731f0834526da25297b0f91a6a3bf3521edacd' 
  AND token = 'cdU2hWIKN168A/Qa0oCiU//dSUEpazRYgEj0yQXjVKM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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