SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b492aedb97353dc1fc63a5d4f44d247534f6066ba3d388f7596dac37c8478fd9' 
  AND token = '3Dmx/xADNxDqwPNBdl+gqAjum8SOCQkkjX+akPzKiIs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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