SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3f4210c869892a670988a2d94704157dc565303f7742601df3317e8a5d0bc4c4' 
  AND token = 'GkMeDwPrEMgP/v1vkSXMoPKYP4bwIrq82XLK4WgowX0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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