SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1b20fd4c7aa854ac5eef2763f937a1232a68ff10a115625b857930e422a22bda' 
  AND token = 'F/4angf253hMwQ1mdVPdHfe+avnCyRhbcRC7SBPPH3U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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