SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6d9b5b2482b147aa8c321e5142836b9ca86ebce995cf1276f3aa529212da00e3' 
  AND token = 'U5fd6f063u6TQWC4EpI1KMRKiBDO2IQrCVs9smLFv7s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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