SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1bfe3a08c46495266f49dfec79963d87b16a345316020ceaaf65741861507bc8' 
  AND token = 'KjpJh/WcHDWu43+oGE/bUU1uSNIFOgG0D1D1reqBHrw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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