SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4a10495e066da473cadab3fa0027cc31da5882ac18b999e978ead424895bcabc' 
  AND token = 'IVHNxAh8oCkQzBSSlbwyFqVIwne/wh76Z4r0mPwqzv4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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