SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ed2cad9a408061286c821d21050e8f83fa278df8d88647d439ae91ecce5b6f58' 
  AND token = 'BCLUv51IbUBhtIiejpz07MrxVIFrEEfGbEywymj+H/A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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