SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c121d2dff0fcc5d61f943945ed4f234cf072340af172260f112f8e78b25e6faf' 
  AND token = 'oPU++eKYuwYF6PsfYeQRUJe9N9hlhNMzZAb8fDCHP9g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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